Filtering devices and methods for filtering liquids, particularly such for filtering water to obtain potable water, are known. Examples are U.S. Pat. Nos. 789,968 and 1,090,283. Such filtering devices generally hold a filtering medium with reactants that can remove harmful or otherwise undesired substances from the filtered water.
WO 2004/071961 discloses a water treatment device and method for treating water. The device includes a water-collecting chamber and a filtration chamber which includes a set of reactants that include a polycation, a polyanion and optionally other components. The filter includes upwardly extending and downward extending circular walls intercalated into the spaces between one another. The water flows through the filter by gravitational force. Another water-filtering device and method is disclosed in WO 2005/092798.